The present invention relates to substrates such as those used in inkjet printheads and the like.
Various inkjet printing arrangements are known in the art and include both thermally actuated printheads and mechanically actuated printheads. Thermal actuated printheads tend to use resistive elements or the like to achieve ink expulsion, while mechanically actuated printheads tend to use piezoelectric transducers of the like.
A representative thermal inkjet printhead has a plurality of thin film resistors provided on a semiconductor substrate. A nozzle plate and barrier layer are provided on the substrate and define the firing chambers about each of the resistors. Propagation of a current or a xe2x80x9cfire signalxe2x80x9d through a resistor causes ink in the corresponding firing chamber to be heated and expelled through the appropriate nozzle.
Ink is typically delivered to the firing chamber through a feed slot that is machined in the semiconductor substrate. The substrate usually has a rectangular shape, with the slot disposed longitudinally therein. Resistors are typically arranged in rows located on both sides of the slot and are preferably spaced approximately equal distances from the slot so that the ink channel length at each resistor is approximately equal. The width of the print swath achieved by one pass of a printhead is approximately equal to the length of the resistor rows, which in turn is approximately equal to the length of the slot.
Feed slots have typically been formed by sand drilling (also known as xe2x80x9csand slottingxe2x80x9d). This method is preferred because it is a rapid, relatively simple and scalable (many substrates may be processed simultaneously) process. While sand slotting affords these apparent benefits, sand slotting is also disadvantageous in that it causes micro cracks in the semiconductor substrate that significantly reduce the substrates fracture strength, resulting in significant yield loss due to cracked die. Low fracture strength also limits substrate length which in turn adversely impacts print swath height and overall print speed.
Other techniques include ultrasonic diamond bit drilling, abrasive sand blasting, YAG laser machining, KOH etching, TMAH etching, and dry plasma etching.
A method of fabricating an inkjet printhead is described, and includes providing a printhead substrate, fabricating a thinfilm structure on the substrate, forming a break trench in a surface region of the substrate in which a feed slot is to be formed, and subsequently abrasively machining the substrate through the break trench to form the feed slot.